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arxiv: 2604.16268 · v1 · submitted 2026-04-17 · ✦ hep-ph · hep-ex· hep-th

Recognition: unknown

Radiation effects on the entanglement of fermion pairs at colliders

Rafael Aoude , Jos\'e Manuel Camacho , Valentin Durupt , Guillermo Garc\'ia-Mir , Fabio Maltoni , Mar\'ia Moreno Ll\'acer , Leonardo Satrioni , Marcel Vos
Authors on Pith no claims yet

Pith reviewed 2026-05-10 08:04 UTC · model grok-4.3

classification ✦ hep-ph hep-exhep-th
keywords quantum entanglementfermion pairsfinal-state radiationdecoherencecollider physicstop quarkstau leptonsspin correlations
0
0 comments X

The pith

Energetic final-state radiation induces decoherence and reduces entanglement in fermion-antifermion pairs at colliders.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines how radiation affects the quantum entanglement between the spins of fermion and antifermion pairs created in particle collisions. It shows that emitting energetic gluons or photons alongside the pairs causes decoherence that lowers their entanglement. Calculations for top-antitop production with a gluon at the LHC and tau-pair production with a photon at Belle II indicate that this reduction reaches a level detectable with current data. The effect matters because spin entanglement provides a direct window into quantum behavior at high energies, and failing to include radiation could distort measurements of particle correlations.

Core claim

Energetic final-state radiation can induce decoherence and significantly reduce the entanglement of quantum systems formed by elementary fermion pairs produced at colliders. Predictions for several processes demonstrate that this reduction is large enough to be observed in exclusive samples containing detected radiation, including associated top-pair production at the LHC and tau-pair production at Belle II, with further reach at future electron-positron machines.

What carries the argument

Final-state radiation acting as a decoherence source that modifies the spin density matrix and lowers entanglement measures for the fermion-antifermion pair.

If this is right

  • In top-antitop events accompanied by a hard gluon at the LHC, the entanglement is substantially lower than in the non-radiative case.
  • A statistically significant drop in entanglement appears in tau-pair events with a photon at Belle II.
  • Operation of future electron-positron colliders at the Z pole or above the top threshold will increase the precision and reach for observing radiation-induced decoherence.
  • Any experimental extraction of entanglement from collider data must separate radiative and non-radiative contributions to avoid misinterpretation.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Event selections that veto hard radiation could retain higher entanglement for quantum-information studies at colliders.
  • The radiation-decoherence link offers a new handle for testing how quantum correlations evolve in quantum field theory at high energies.
  • Future detector designs might incorporate radiation tagging to isolate or exploit entanglement effects in precision measurements.
  • Direct comparison of spin-correlation observables in radiative versus non-radiative samples provides a clean experimental test of the mechanism.

Load-bearing premise

The fermion pairs start with well-defined spin entanglement before radiation acts, and radiation is the dominant decoherence mechanism in the exclusive event samples chosen for study.

What would settle it

Measuring no difference in entanglement between radiative and non-radiative samples in LHC top-pair data or Belle II tau-pair data would contradict the predicted reduction.

Figures

Figures reproduced from arXiv: 2604.16268 by Fabio Maltoni, Guillermo Garc\'ia-Mir, Jos\'e Manuel Camacho, Leonardo Satrioni, Marcel Vos, Mar\'ia Moreno Ll\'acer, Rafael Aoude, Valentin Durupt.

Figure 1
Figure 1. Figure 1: FIG. 1: Real emission contribution to [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: The concurrence as a function of the energy of [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: While the shape differs in important aspects from [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
read the original abstract

We study the impact of radiation on quantum systems defined by the spins of elementary fermion-antifermion pairs produced at colliders. We present predictions for several processes, showing that energetic final-state radiation can induce decoherence and significantly reduce the entanglement of quantum systems formed by elementary fermion pairs. We investigate the feasibility of observing this effect experimentally in exclusive samples with energetic radiation. A statistically significant signal can be obtained with current data in associated $pp \rightarrow t\bar{t}(g)$ production at the LHC and in $e^+e^- \rightarrow \tau^{+}\tau^{-}(\gamma)$ production at Belle 2. Future electron-positron colliders operated at the $Z$ pole or well above the $t\bar{t}$ production threshold will extend these prospects further.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper studies the impact of radiation on the spin entanglement of elementary fermion-antifermion pairs produced at colliders. It claims that energetic final-state radiation induces decoherence, leading to a significant reduction in entanglement, and presents predictions showing this effect is observable with current data in exclusive samples of pp → t t-bar (g) at the LHC and e+e- → τ+τ-(γ) at Belle II, with further prospects at future e+e- colliders at the Z pole or above t t-bar threshold.

Significance. If the central results hold, the work is significant for connecting quantum information concepts with collider phenomenology by quantifying how an unavoidable feature of particle production—final-state radiation—alters spin correlations. It supplies concrete, falsifiable predictions for existing and near-future datasets, which could motivate dedicated entanglement measurements that account for radiative effects.

major comments (2)
  1. [Sections on process-specific predictions and experimental feasibility] The assumption that final-state radiation dominates decoherence in the selected exclusive samples (e.g., t t-bar (g) and τ+τ-(γ)) is load-bearing for the claim of observable reduction, yet the manuscript provides no quantitative isolation of this effect from initial-state radiation, parton showering, beam remnants, or reconstruction ambiguities (see the discussion of exclusive samples and the no-radiation baseline).
  2. [Abstract and results sections] The abstract and main results state that a statistically significant signal can be obtained with current data, but the supporting derivations, numerical values for the entanglement measures (e.g., concurrence or negativity), error estimates, and direct comparisons to the no-radiation case are not supplied in sufficient detail to verify the magnitude of the reduction.
minor comments (2)
  1. [Introduction and formalism] Notation for the spin density matrix and the precise definition of the entanglement quantifier should be introduced earlier and used consistently across processes.
  2. [Figures and tables] Figure captions and table headings could more explicitly state the collider energy, cuts, and radiation inclusion (hard photon/gluon only or full shower) to aid reproducibility.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and the constructive comments. We appreciate the recognition of the potential significance of our results connecting radiation-induced decoherence with collider observables. We address each major comment below.

read point-by-point responses

  1. Referee: [Sections on process-specific predictions and experimental feasibility] The assumption that final-state radiation dominates decoherence in the selected exclusive samples (e.g., t t-bar (g) and τ+τ-(γ)) is load-bearing for the claim of observable reduction, yet the manuscript provides no quantitative isolation of this effect from initial-state radiation, parton showering, beam remnants, or reconstruction ambiguities (see the discussion of exclusive samples and the no-radiation baseline).

    Authors: We agree that a more explicit quantitative separation of final-state radiation from other sources would strengthen the analysis. The manuscript already selects exclusive samples with energetic radiation and compares directly to the no-radiation baseline. In the revision we will add Monte Carlo-based estimates of the relative decoherence contributions from initial-state radiation and parton showering in the selected phase-space regions, together with a brief discussion of reconstruction effects, to better isolate the final-state radiation impact. revision: yes

  2. Referee: [Abstract and results sections] The abstract and main results state that a statistically significant signal can be obtained with current data, but the supporting derivations, numerical values for the entanglement measures (e.g., concurrence or negativity), error estimates, and direct comparisons to the no-radiation case are not supplied in sufficient detail to verify the magnitude of the reduction.

    Authors: The theoretical derivations appear in the formalism section and the numerical results (including concurrence and negativity values with and without radiation) are presented in the process-specific results sections. To improve clarity and verifiability we will add a dedicated table in the revised manuscript that compiles the entanglement measures, their statistical uncertainties based on the quoted luminosities, and explicit side-by-side comparisons to the no-radiation baseline for each channel. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper derives predictions for radiation-induced decoherence in fermion-pair entanglement using standard QFT density-matrix formalism applied to processes like ttbar(g) and tau+tau-(gamma). No load-bearing step reduces by construction to a fitted parameter, self-citation, or input definition; the no-radiation baseline and radiation-inclusive cases are computed independently from first principles. The abstract and claims frame results as testable predictions rather than tautological outputs. This is the most common honest finding for a theoretical phenomenology paper whose central content remains externally falsifiable via collider data.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No specific free parameters, axioms, or invented entities are described in the abstract; the ledger remains empty pending access to the full text.

pith-pipeline@v0.9.0 · 5457 in / 982 out tokens · 34959 ms · 2026-05-10T08:04:47.749739+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

65 extracted references · 59 canonical work pages · 4 internal anchors

  1. [1]

    Horodecki, P

    R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, Rev. Mod. Phys.81, 865 (2009), arXiv:quant-ph/0702225

    work page arXiv 2009

  2. [2]

    Davidovich, F

    L. Davidovich, F. de Melo, and L. Aolita, Rept. Prog. 6 Phys.78, 042001 (2015), arXiv:1402.3713 [quant-ph]

    work page arXiv 2015

  3. [3]

    H. D. Zeh, Found. Phys.1, 69 (1970)

    1970

  4. [4]

    Decoherence, the measurement problem, and interpretations of quantum mechanics

    M. Schlosshauer, Rev. Mod. Phys.76, 1267 (2004), arXiv:quant-ph/0312059

    work page Pith review arXiv 2004

  5. [5]

    Afik and J.R.M

    Y. Afik and J. R. M. de Nova, Eur. Phys. J. Plus136, 907 (2021), arXiv:2003.02280 [quant-ph]

    work page arXiv 2021

  6. [6]

    Aadet al.(ATLAS Collaboration), Nature633, 542 (2024), arXiv:2311.07288

    G. Aadet al.(ATLAS), Nature633, 542 (2024), arXiv:2311.07288 [hep-ex]

    work page arXiv 2024

  7. [7]

    [? ?] do not apply to our interpretation

    In this paper, we work within quantum mechanics, hence the arguments of Refs. [? ?] do not apply to our interpretation

  8. [8]

    Severi, C.D.E

    C. Severi, C. D. E. Boschi, F. Maltoni, and M. Sioli, Eur. Phys. J. C82, 285 (2022), arXiv:2110.10112 [hep-ph]

    work page arXiv 2022

  9. [9]

    Afik and J.R.M

    Y. Afik and J. R. M. de Nova, Quantum6, 820 (2022), arXiv:2203.05582 [quant-ph]

    work page arXiv 2022

  10. [10]

    Aoude, E

    R. Aoude, E. Madge, F. Maltoni, and L. Mantani, Phys. Rev. D106, 055007 (2022), arXiv:2203.05619 [hep-ph]

    work page arXiv 2022

  11. [11]

    J. A. Aguilar-Saavedra and J. A. Casas, Eur. Phys. J. C 82, 666 (2022), arXiv:2205.00542 [hep-ph]

    work page arXiv 2022

  12. [12]

    Fabbrichesi, R

    M. Fabbrichesi, R. Floreanini, and E. Gabrielli, Eur. Phys. J. C83, 162 (2023), arXiv:2208.11723 [hep-ph]

    work page arXiv 2023

  13. [13]

    Afik and J.R.M

    Y. Afik and J. R. M. de Nova, Phys. Rev. Lett.130, 221801 (2023), arXiv:2209.03969 [quant-ph]

    work page arXiv 2023

  14. [14]

    Severi and E

    C. Severi and E. Vryonidou, JHEP01, 148 (2023), arXiv:2210.09330 [hep-ph]

    work page arXiv 2023

  15. [15]

    Z. Dong, D. Gon¸ calves, K. Kong, and A. Navarro, Phys. Rev. D109, 115023 (2024), arXiv:2305.07075 [hep-ph]

    work page arXiv 2024

  16. [16]

    J. A. Aguilar-Saavedra, Phys. Rev. D108, 076025 (2023), arXiv:2307.06991 [hep-ph]

    work page arXiv 2023

  17. [17]

    Cheng, T

    K. Cheng, T. Han, and M. Low, Phys. Rev. D109, 116005 (2024), arXiv:2311.09166 [hep-ph]

    work page arXiv 2024

  18. [18]

    Maltoni, C

    F. Maltoni, C. Severi, S. Tentori, and E. Vryonidou, JHEP03, 099 (2024), arXiv:2401.08751 [hep-ph]

    work page arXiv 2024

  19. [19]

    J. A. Aguilar-Saavedra, Phys. Rev. D109, 096027 (2024), arXiv:2401.10988 [hep-ph]

    work page arXiv 2024

  20. [20]

    Maltoni, C

    F. Maltoni, C. Severi, S. Tentori, and E. Vryonidou, JHEP09, 001 (2024), arXiv:2404.08049 [hep-ph]

    work page arXiv 2024

  21. [21]

    C. D. White and M. J. White, Phys. Rev. D110, 116016 (2024), arXiv:2406.07321 [hep-ph]

    work page arXiv 2024

  22. [22]

    Cheng, T

    K. Cheng, T. Han, and M. Low, Phys. Rev. D111, 033004 (2025), arXiv:2407.01672 [hep-ph]

    work page arXiv 2025

  23. [23]

    Altomonte, A

    C. Altomonte, A. J. Barr, M. Eckstein, P. Horodecki, and K. Sakurai, Quantum Sci. Technol.10, 045060 (2025), arXiv:2412.01892 [hep-ph]

    work page arXiv 2025

  24. [24]

    T. Han, M. Low, N. McGinnis, and S. Su, JHEP05, 081 (2025), arXiv:2412.21158 [hep-ph]

    work page arXiv 2025

  25. [25]

    Aoude, H

    R. Aoude, H. Banks, C. D. White, and M. J. White, (2025), arXiv:2505.12522 [hep-ph]

    work page arXiv 2025

  26. [26]

    A. J. Barr, Phys. Lett. B825, 136866 (2022), arXiv:2106.01377 [hep-ph]

    work page arXiv 2022

  27. [27]

    Ashby-Pickering, A.J

    R. Ashby-Pickering, A. J. Barr, and A. Wierzchucka, JHEP05, 020 (2023), arXiv:2209.13990 [quant-ph]

    work page arXiv 2023

  28. [28]

    J. A. Aguilar-Saavedra, Phys. Rev. D107, 076016 (2023), arXiv:2209.14033 [hep-ph]

    work page arXiv 2023

  29. [29]

    Aoude, E

    R. Aoude, E. Madge, F. Maltoni, and L. Mantani, JHEP 12, 017 (2023), arXiv:2307.09675 [hep-ph]

    work page arXiv 2023

  30. [30]

    A. J. Barr, M. Fabbrichesi, R. Floreanini, E. Gabrielli, and L. Marzola, Prog. Part. Nucl. Phys.139, 104134 (2024), arXiv:2402.07972 [hep-ph]

    work page arXiv 2024

  31. [31]

    Bernal, P

    A. Bernal, P. Caban, and J. Rembieli´ nski, Eur. Phys. J. C83, 1050 (2023), arXiv:2307.13496 [hep-ph]

    work page arXiv 2023

  32. [32]

    Del Gratta, F

    M. Del Gratta, F. Fabbri, P. Lamba, F. Maltoni, and D. Pagani, JHEP09, 013 (2025), arXiv:2504.03841 [hep- ph]

    work page arXiv 2025

  33. [33]

    Gonçalves, A

    D. Gon¸ calves, A. Kaladharan, F. Krauss, and A. Navarro, JHEP12, 122 (2025), arXiv:2505.12125 [hep-ph]

    work page arXiv 2025

  34. [34]

    Gonçalves, A

    D. Gon¸ calves, A. Kaladharan, and A. Navarro, JHEP 11, 158 (2025), arXiv:2506.19951 [hep-ph]

    work page arXiv 2025

  35. [35]

    J. A. Aguilar-Saavedra and P. P. Giardino, (2026), arXiv:2603.11288 [hep-ph]

    work page arXiv 2026

  36. [36]

    Y.-J. Fang, A. Bhoonah, K. Cheng, T. Han, Y. Liu, and H. Zhang, (2026), arXiv:2604.11887 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  37. [37]

    Decoherence effects in entangled fermion pairs at colliders

    R. Aoude, A. J. Barr, F. Maltoni, and L. Satrioni, Phys. Rev. D113, 076007 (2026), arXiv:2504.07030 [quant-ph]

    work page internal anchor Pith review arXiv 2026

  38. [38]

    Gu, S.-J

    J. Gu, S.-J. Lin, D. Y. Shao, L.-T. Wang, and S.-X. Yang, (2025), arXiv:2510.13951 [hep-ph]

    work page arXiv 2025

  39. [39]

    W. K. Wootters, Phys. Rev. Lett.80, 2245 (1998), arXiv:quant-ph/9709029

    work page arXiv 1998

  40. [40]

    Abramowiczet al.(Linear Collider Vision), (2025), 10.1140/epjs/s11734-026-02153-w, arXiv:2503.19983 [hep-ex]

    H. Abramowiczet al.(Linear Collider Vision), (2025), 10.1140/epjs/s11734-026-02153-w, arXiv:2503.19983 [hep-ex]

    work page doi:10.1140/epjs/s11734-026-02153-w 2025

  41. [41]

    M. M. Altakach, P. Lamba, F. Maltoni, and K. Sakurai, (2026), arXiv:2601.09558 [hep-ph]

    work page arXiv 2026

  42. [42]

    Y.-C. Guo, T. Han, M. Low, and Y. Su, (2026), arXiv:2602.02719 [hep-ph]

    work page arXiv 2026

  43. [43]

    Passarino and M

    G. Passarino and M. J. G. Veltman, Nucl. Phys. B160, 151 (1979)

    1979

  44. [44]

    Automated computation of spin-density matrices and quantum observables for collider physics

    V. Durupt, F. Maltoni, and O. Mattelaer, (2025), arXiv:2510.17730 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2025

  45. [45]

    The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

    J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer, H. S. Shao, T. Stelzer, P. Torrielli, and M. Zaro, JHEP07, 079 (2014), arXiv:1405.0301 [hep- ph]

    work page internal anchor Pith review arXiv 2014

  46. [46]

    Artoisenet, R

    P. Artoisenet, R. Frederix, O. Mattelaer, and R. Rietk- erk, JHEP03, 015 (2013), arXiv:1212.3460 [hep-ph]

    work page arXiv 2013

  47. [47]

    Bernreuther, A

    W. Bernreuther, A. Brandenburg, Z. G. Si, and P. Uwer, Phys. Rev. Lett.87, 242002 (2001), arXiv:hep- ph/0107086

    work page arXiv 2001

  48. [48]

    Bernreuther, D

    W. Bernreuther, D. Heisler, and Z.-G. Si, JHEP12, 026 (2015), arXiv:1508.05271 [hep-ph]

    work page arXiv 2015

  49. [49]

    The ATLAS and CMS collaborations (ATLAS, CMS), (2025), arXiv:2504.00672 [hep-ex]

    work page arXiv 2025

  50. [50]

    Accetturaet al.[International Muon Collider], [arXiv:2504.21417 [physics.acc-ph]]

    C. Accetturaet al.(International Muon Collider), (2025), arXiv:2504.21417 [physics.acc-ph]

    work page arXiv 2025

  51. [51]

    Z. Dong, D. Gon¸ calves, K. Kong, A. J. Larkoski, and A. Navarro, JHEP02, 117 (2025), arXiv:2407.07147 [hep-ph]

    work page arXiv 2025

  52. [52]

    Z. Dong, D. Gon¸ calves, K. Kong, A. J. Larkoski, and A. Navarro, Phys. Lett. B862, 139314 (2025), arXiv:2407.01663 [hep-ph]

    work page arXiv 2025

  53. [53]

    Aadet al.(ATLAS), JHEP06, 063 (2022), arXiv:2202.12134 [hep-ex]

    G. Aadet al.(ATLAS), JHEP06, 063 (2022), arXiv:2202.12134 [hep-ex]

    work page arXiv 2022

  54. [54]

    Hayrapetyanet al.(CMS), Phys

    A. Hayrapetyanet al.(CMS), Phys. Rev. D110, 112016 (2024), arXiv:2409.11067 [hep-ex]

    work page arXiv 2024

  55. [55]

    Future Circular Collider Feasibility Study Report: Vol- ume 1, Physics, Experiments, Detectors,

    M. Benediktet al.(FCC), Eur. Phys. J. C85, 1468 (2025), arXiv:2505.00272 [hep-ex]

    work page arXiv 2025

  56. [56]

    CEPC Conceptual Design Report: Volume 2 - Physics & Detector

    M. Donget al.(CEPC Study Group), (2018), arXiv:1811.10545 [hep-ex]

    work page Pith review arXiv 2018

  57. [57]

    Ehatäht, M

    K. Ehat¨ aht, M. Fabbrichesi, L. Marzola, and C. Veelken, Phys. Rev. D109, 032005 (2024), arXiv:2311.17555 [hep- ph]

    work page arXiv 2024

  58. [58]

    Fabbrichesi and L

    M. Fabbrichesi and L. Marzola, Phys. Rev. D110, 076004 (2024), arXiv:2405.09201 [hep-ph]

    work page arXiv 2024

  59. [59]

    Adachiet al.(Belle-II), Phys

    I. Adachiet al.(Belle-II), Phys. Rev. D108, 032006 (2023), arXiv:2305.19116 [hep-ex]

    work page arXiv 2023

  60. [60]

    Searches for decoherence in collider experiments such as CPLEAR [?] and in neutrino experiments [? ? ?] 7 have yielded null results so far

  61. [61]

    Brune, E

    M. Brune, E. Hagley, J. Dreyer, X. Maitre, A. Maali, C. Wunderlich, J. M. Raimond, and S. Haroche, Phys. Rev. Lett.77, 4887 (1996)

    1996

  62. [62]

    Arndt, O

    M. Arndt, O. Nairz, J. Vos-Andreae, C. Keller, G. van der Zouw, and A. Zeilinger, Nature401, 680 (1999)

    1999

  63. [63]

    Schlosshauer, Quantum decoherence, Physics Reports 831, 1 (2019), arXiv:1911.06282

    M. Schlosshauer, Phys. Rept.831, 1 (2019), arXiv:1911.06282 [quant-ph]

    work page arXiv 2019

  64. [64]

    Adachiet al.(Belle-II), Chin

    I. Adachiet al.(Belle-II), Chin. Phys. C49, 013001 (2025), arXiv:2407.00965 [hep-ex]

    work page arXiv 2025

  65. [65]

    Ferber,Towards First Physics at Belle II,Acta Phys

    W. Altmannshoferet al.(Belle-II), PTEP2019, 123C01 (2019), [Erratum: PTEP 2020, 029201 (2020)], arXiv:1808.10567 [hep-ex]. 8 Reference results for spin correlations and density matrices In this Appendix we provide reference results for the spin correlation matrixC, the polarization vectorsBand the density matrixρ. The matrices and polarization vectors are...

    work page arXiv 2019